Displays are found in numerous types of electronic devices such as electronic book (“eBook”) readers, cellular telephones, smart phones, portable media players, tablet computers, wearable computers, laptop computers, netbooks, desktop computers, televisions, appliances, home electronics, automotive electronics, augmented reality devices, and so forth. Displays may present various types of information, such as user interfaces, device operational status, digital content items, and the like, depending on the kind and purpose of the associated device. The appearance and quality of a display can affect a user's experience with the electronic device and the content presented thereon. Energy consumption of a display can also affect a user's experience regarding battery life and environmental impact. Accordingly, finding ways to enhance user experience and reduce environmental stress continues to be a priority.
Increased multimedia use imposes high demands on designs of displays, as content available for mobile use becomes visually richer. In a liquid-crystal display (LCD), energy efficiency, among other things, can be determined by a backlight or frontlight design. Many transmissive displays use backlights that light a display to enable a viewer to see content on the display that can otherwise be difficult to see without the backlights. In another example, reflective displays use frontlights to improve visibility of content on displays, particularly in low light situations. Displays configured with backlights and/or frontlights can incorporate one or more light guides to direct light from a light source onto or through the display. In some applications, a light source can have a relatively small area, such as in the case of a light emitting diode (LED).